Conventional devices exist for connecting springs together in spring assemblies used in mattresses and cushions. Furthermore, such devices are further used to provide, in conjunction with the connected springs, a more uniform load supporting surface than that formed by the springs alone, the connecting devices serving to support loads applied in-between the springs of a spring assembly where gaps in the load support would otherwise occur.
For example, McMains, U.S. Pat. No. 160,274, discloses such a connecting device formed from a shaped wire. Specifically, the wire is shaped to form four arms with the end of each arm including a C-shaped portion for grasping a coil of a spring. Furthermore, parallel wire segments form each arm and the overall shape of the connecting device is a right angle cross having arms of equal length. The device is used for connecting and binding together of a group of four springs at their base and at their top in a mattress with the ends of the wire arms being bent around the top or bottom coil of the springs. McMains teaches that the connecting devices provide equal and even adjustment of the surface of a mattress when a load is applied by filling the dead space otherwise occurring between the four springs. However, McMains does not disclose any means for varying the support characteristics provided by each connecting device, the support characteristics of each connecting device depending upon the rigidity of the shaped wire forming the connecting device and the length between the connected springs which the connecting piece spans, i.e., the length of each arm.
Warner, U.S. Pat. No. 453,850, discloses another connecting device formed from two flat rectangular pieces that are crossed obliquely and secured together at their intersection to form a right angle cross having arms of equal length. As in McMains, the ends of each arm are bent around a top coil of a connected coil spring, and the connecting device serves the same function as the connecting device in McMains. Unlike in McMains, each arm appears to be solid and appears to have a uniform thickness. Nevertheless, Warner fails to address any means for varying the support characteristics of the connecting device for tailoring the overall support characteristics of the spring assembly, the support characteristics of each connecting device depending upon the rigidity of the material from which the connecting device is formed and the length size of the connecting device, i.e., size of the rectangular pieces forming the connecting device.
Yet another connecting device is disclosed in FIG. 5 of Cleaveland, U.S. Pat. No. 392,009. Called a "spider," the connecting device consists of a metallic plate having four arms each connects to and extends radially outwardly from an annular ring defining a circular opening through the center of the spider. Each arm is solid and of uniform thickness, and the end of each arm is hook shaped for embracing an upper coil of one of four connected coil springs. Cleaveland discloses that each spider is preferably produced in solid form from malleable castings or from plate material cut and pressed to the specified form. Like in McMains and Warner, no means is disclosed or suggested by Cleaveland for varying the support characteristics of the spider for tailoring the overall support characteristics of the spring assembly, the support characteristics of each arm again depending upon the rigidity of the material forming the spider and the size of the spider including the length of the arms and the radius of the annular ring.
Vincent, U.S. Pat. No. 1,273,428, discloses a flat sheet-metal plate with arms for attachment to a top coil of a coil spring itself and, unlike the connecting devices in McMains and Vincent, not for connecting together a plurality of coil springs. Specifically, the plate in Vincent is secured to a single coil of a coil spring and small helical connecting springs are used for connecting an arm of one plate to an arm of another plate secured to the top of another coil spring. In one embodiment, each connecting spring is attached to a coil through an aperture in an attached plate. In another embodiment, each connecting spring extends over an arm prior to its attachment to a coil whereby the connecting spring is retained by the arm's attachment to the coil; the apertures in the arms in this embodiment are therefore omitted. Each plate serves to equalize the loads applied to the surface of the mattress across the top of each coil spring. The arms of the plate being attached to the top coil of a single coil spring also serve to hold the coil spring in proper position and alignment. As is apparent, the device in Vincent does not extend between the spaces between the coil springs and only indirectly supports a load applied in such spaces to the extent that connecting springs disposed there are connected to and supported by the plates. Furthermore, Vincent fails to disclose or suggest a means for varying the support characteristics of the spider for tailoring the overall support characteristics of the spring assembly.
The connecting device of the present invention represents an improvement over the connecting devices of the prior art discussed above because, among other features, the connecting device includes a stiffening portion which can be varied during the manufacturing thereof to vary the load support characteristics of the connecting device and, consequently, each connecting device can be customized to tailor the load support characteristics of a spring assembly in which connecting devices are used. Furthermore, as a consequence of the provision of a stiffening portion, the support characteristics of the connecting device can be varied with varying the materials from which the connecting device is constructed and without varying the length of the arms or the overall dimensions of the connecting device.